To the Editor: Neisseria meningitidis serogroup X was first
described in the 1960s and has been found to be responsible of rare
cases of invasive meningococcal diseases, in particular, meningitis, in
North America, Europe, Australia, Africa, and the People's Republic
of China (1-3). This serogroup has recently emerged in Africa as an
increasing cause of meningitis; unfortunately, it is not covered by
current vaccine programs. Serogroup X outbreaks have been reported in
Niger, Ghana, and Kenya (4-6). In particular, in Niger during
January-June 2006, N. meningitidis serogroup X represented 51% of
confirmed cases of meningitis (4).

To investigate the population structure of serogroup X meningococci
isolated during recent decades in Africa, Europe, and North America,
Gagneux et al. (1) compared the molecular characteristics among them.
That study highlighted a low genetic variability between African
serogroup X strains, which contrasts with higher genetic variability
among isolates from Europe and the United States (1).

We describe a case of invasive meningococcal disease caused by a
serogroup X N. meningitidis strain isolated in Italy. The patient was a
55-year-old Italian woman with no immune deficiency. The onset of
disease started quickly with high fever (39[degrees]C) on June 1, 2009.
No contacts with persons coming from abroad were reported. This case was
diagnosed on the basis of clinical signs and symptoms and results of
laboratory confirmatory tests, including blood culture. The patient
received ceftriaxone (2 g/day) for 7 days with a favorable outcome.

The strain was susceptible to penicillin G, rifampin,
ciprofloxacin, and ceftriaxone, as determined by Etest method
(bioMerieux, Florence, Italy). The breakpoints were those recommended by
the Clinical and Laboratory Standards Institute (7). Serogroup was
determined by serum agglutination, and serotype/subtype, NT:P1.15, 19
were determined by standard whole-cell ELISA with monoclonal antibodies
(obtained from the National Institute for Biological Standards and
Control, South Mimms, UK) (8).

PorA variable regions, FetA, and multilocus sequence typing
analyses were performed according to standard procedures from the
Neisseria Multi Locus Sequence Typing Web site
(http://pubmlst.org/neisseria). The isolate from Italy had the pattern
PorA VR1-19, VR2-15, and VR3-36; F5-5 and sequence type (ST)-2888. The
same ST was already described in Greece in 2002 but in a noninvasive
strain (http://pubmlst.org/neisseria).

The pattern obtained by pulsed-field gel electrophoresis (9), using
the rare-cutting enzyme NheI, (data not shown), was identical to
patterns found among meningococci X strains isolated in United Kingdom
and belonging to ST-750, clonal group X-II (1). In particular, ST-2888
resembles, except for gdh gene sequence, ST-2317, which was found among
the X meningococci isolated in the United Kingdom in 2002 with phenotype
X:4:P1.7 (http://pubmlst.org/neisseria).

Our data document a rare case of invasive meningococcal meningitis
in Italy, caused by N. meningitidis serogroup X ST-2888. Future
surveillance data may be able to determine epidemiologic influences,
likely emanating from nearby countries, on the spread of such a strain
into Italy.

DOI: 10.3201/eid1602.091553

Acknowledgments

We thank Anna Pavan, Maria Gramegna, and Luigi Macchi for the
collaboration in the Italian Surveillance System for Invasive Bacterial
Diseases.

This work was partially funded by the Ministry of Health-CCM
Project 116 "Surveillance of invasive bacterial diseases,"
2007-2009.